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Chemistry: Catalase Sample Questions

We did the catalse test in class and I have been able to answer some questions but not all.
Questions:
1) Provide an example of reduction reaction performed by cells in which hydrogen is not added to the reduced compound. (I think it deals with hydrogen peroxide--> to water and oxygen)

2) Would a flase positive due to the reaction between the loop and hydrogen peroxide be due to a lack of specificy or sensitivity of the test system?

3) If a weakly catalase-positive organism itinitially gives a false-negative result and is not checked under the miicroscope, would the result be due to a lack of specificity or sensitivity of the test system?

4) Why is it advisable to perform this test on a known catalase-positive organism simultaneously with the organism you are checking?

5) What is the purpose of adding hydrogen peroxide to the uninoculated tube?

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Solution Preview

(1) Provide an example of reduction reaction performed by cells in which hydrogen is not added to the reduced compound.

You're correct. 2 H2O2 ----> 2 H2O + O2

(2) Would a false positive due to the reaction between the loop and hydrogen peroxide be due to a lack of specificity or sensitivity of the test system?

Response: Such a false positive reaction would be due to a lack of specificity in the test system. In other words, the test system is sensitive enough, the problem being that "other" things going on in the test system also gives a "positive" result. Therefore, the issue here has to do with a lack of specificity.

(3) If a weakly catalase-positive organism itinitially gives a false-negative result and ...

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